The overall objectives of this project are to 1) delineate the mycoplasm-cell interaction which results in interferon production by mammalian cells, and 2) determine the possible significance of mycoplasma-induced interferon in protection against viral disease in vivo. The mechanisms of interferon induction are being studied using a sheep leukocyte in vitro system. In vivo studies are being conducted in mice to determine the effect of mycoplasma-mediated interferon on susceptibility of the host to Herpes virus hominis and encephalomyocarditis virus infections. Mycoplasma-mediated hyporeactivity to other interferon inducers such as Newcastle disease virus, poly I:C and tilorone is also being investigated.